A wireless device (e.g., a cellular phone or a smartphone) in a wireless communication system may transmit and receive data for two-way communication. The wireless device may include a transmitter for data transmission and a receiver for data reception. For data transmission, the transmitter may modulate a radio frequency (RF) carrier signal with data to generate a modulated RF signal, amplify the modulated RF signal to generate a transmit RF signal having the proper output power level, and transmit the transmit RF signal via an antenna to a base station. For data reception, the receiver may obtain a received RF signal via the antenna and may amplify and process the received RF signal to recover data sent by the base station.
The wireless device may support two-way communication on multiple frequency bands and/or multiple radio technologies. The wireless device may also support carrier aggregation, which is simultaneous operation on multiple carriers. A carrier may refer to a range of frequencies used for two-way communication and may be associated with certain characteristics. For example, a carrier may be associated with a communication system (e.g., Wi-Fi, cellular) and/or a communication protocol (e.g., IEEE 802.11, BLUETOOTH, LTE, etc.) A carrier may also be referred to as a component carrier (CC), a frequency channel, a cell, etc.
When multiple transmitters operate simultaneously, communication signals associated with a first transmitter may undesirably interfere with communication signals associated with a second transmitter. For example, communication signals from the second transmitter may cause intermodulation distortion in the first communication signal.
Thus, there is a need to improve performance of multiple transmitters in wireless devices, especially wireless devices supporting carrier aggregation.